Method of fabricating rotor assemblies



June 14, 1966 D. K. EMMERMANN ETAL 3,

METHOD OF FABRIGATING ROTOR ASSEMBLIES Driginal Filed May 16, 1962 5 Sheets-Sheet 1 $4 INVENTORS DIETER K. EMMERMANN JOHN H. DAVIDS WALLACE E.JOHNSON FM, flit widow June 14, 1966 D. K. EMMERMANN ETAL 3,255,514

METHOD OF FABRICATING ROTOR ASSEMBLIES Original Filed May 16, 1962 5 Sheets-Sheet z INVENTORS DIETER K. EMMERMANN JOHN H DAVIDS WALLACE E.JOHNSON 6 M1424} @Z M (f Malays.

J1me 1966 D. K. EMMERMANN ETAL 3,

METHOD OF FABRICATING ROTOR ASSEMBLIES Original Filed May 16, 1962 5 Sheet 5 3 JILHH' lad .nlmlmih ,i 313 318 I T 9 T1O r i1 mu 3Z6 316 INVENTORS DIETER K. EMMERMANN JOHN H. DAVIDS WALLACE E. JOHNSON June 14, 1966 D. K. EMMERMANN ETAL METHOD OF FABRICATING ROTOR ASSEMBLIES W m Wu 5 H mmmu mn N m k. EM .E a VMH m 1'11 N E E 1g m m w U w ,M v M m & 4 5 I llllllllllllllllllllllllllll I,

Original Filed May 16, 1962 BY W June 14, 1966 D. K. EMMERMANN ETAL 3,255,514

METHOD OF FABRICATING ROTOR ASSEMBLIES Criginal Filed May 16, 1962 5 Sheets-Sheet 5 7 1 44 144 INVENTORS DIETER K. EMMERMANN 7 JOHN H. DAVIDS BY WALLACE E.JOHNSON United States Patent METHOD OF FABRICATING ROTOR ASSEMBLIES Dieter K. Emmermann, John H. Davids, and Wallace E. Johnson, all of Beloit, Wis., assignors to Desalination Plants (Developers of Zarchin Process) Limited, Tel

. Aviv, Israel, a limited company of Israel Original application May 16, 1962, Ser. No. 195,118, now Patent No. 3,202,343, dated Aug. 25, 1965. Divided and this application Dec. 2, 1964, Ser. No. 415,345

8 Claims. (Cl. 29-1563) This is a divisionof application Serial No. 195,118,

. filed May 16, 1962, now Patent No. 3,202,343.

This invention relates to an improvement in a method of fabricating fluid-displacement devices and more particularly relates to an improved method of fabricating a fluid compressor provided for operation under subatmospheric pressure conditions. The method of the present invention is hereinafter described in connection with a system for producing sweet Water from sea water, but it must be appreciated that the present invention is capable of application in other fields.

Our associates and we have developed a system for desalination which produces large volumes of sweet water economically, and this is the subject of the copending United States Patent application, Serial No. 103,114, filed April '14, 1961, for Methods, Systems, and Apparatus for Separating Solute in Substantially Pure Form From Solutions, now abandoned which is hereby incorporated herein by reference.

This application relates to the construction and arrangement of a compressor which may be employed in this system. In this system sea water is flash-evaporated in a low-pressure evaporating chamber to form pure water vapor, pure ice, and concentrated brine. The compressor withdraws the vapor from that chamber and delivers it to a low-pressure condensing chamber where the vapor and ice are brought together to condense the vapor and simultaneously melt the ice to produce the final sea-water product.

As will hereinafter appear, a-compressor of this type for use in vacuum-freezing systems must move and handle a large volume of vapor at low pressure, will be of great size and have a rotor which operates at high speed. The

FIG. 9 is a view in section taken along line 9-9 of FIG. 5.

FIG. 10 is a view in section taken along line 1010 of FIG. 5.

FIG. 11 is a view in section taken along line 1111 of FIG. 5.

FIG. 12 is a view similar to FIG. 6 illustrating a pair of compressor blades before bending thereof for seating in the rotor hub.

FIG. 13 is a fragmentary view of the inducer rotor with the blade blank of FIG. 5 bent to form a pair of blades having the common bight thereof disposed in the rotor.

FIG. 14 is a view in section taken along line 14-14 of FIG. 13 illustrating the first step in contouring the 'blade common 'bight to the rotor.

FIG. 15 is a view similar to FIG. 14 illustrating the second step in contouring the blade bight.

FIG. 16 is a view similar to FIG. 14 illustrating the blade bight contoured to the rotor and locked in place, and

FIG. 17 is an enlarged fragmentary view in elevation illustrating the step of spreading the common bight of a pair of blades.

GENERAL DESCRIPTION OF THE SYSTEM The desalination systemfwith which the compressor of the present invention is used, is shown as a general layout in FIG. 1, the novel compressor being disposed in the upper central portion of FIG. 1. The general arrangement of this system will be first briefly described.

Sea water, which is at ambient temperature, and which has been filtered to remove floating material and other solids is brought into the system through sea water inlet compressor is subject to low pressure at both its intake and discharge outlets. It is important that the impeller be as light as possible, because of the speed at which it operates.

Another object of the present invention is to provide a new and improved method of assembling rotor blades and rotor.

These and other objects and advantages will become more readily apparent as the description proceeds and is read in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic layout of a desalination system.

FIG. 2 is an enlarged fragmentary view in partial section of the compressor and chambers arrangement of FIG. 1.

FIG. 3 is an enlarged fragmentary detailed view of the connection between the inducer rotor and blades of the inducer assembly of FIG. 2.

FIG. 4 is an enlarged fragmentary detailed view of a compressor rotor employed in the arrangement of FIG. 2.

FIG. 5 is a detailed side View of a pair of inducer blades before bending thereof to seat the blades in the rotor hub.

FIG. 6 is a View in side elevation of an inducer blade blank from which the blades of FIG. 5 are formed.

FIG. 7 is a view in top elevation of the blades of FIG. 6.

FIG. 8 is a view in section taken along line 8-8 of FIG. 5.

pipe 10 and passes through deaerator 12 where dissolved gas is removed from the sea water. The sea water is then delivered by pump 14 to heat exchanger 16, where the incoming sea water is placed in heat-exchange relationship with the potable water final product and concentrated brine being withdrawn from the system.

The sea water entering the system will be normally at ambient temperature, such as for example 77 F. and normally contains about 3.5% by weight of salt.

The sea water leaving heat exchanger 16 will be at a temperature of approximately 30.2 F. and is delivered through pipe 18 into the evaporating chamber 20. The sea water enters the evaporating chamber at the central hub of a distributor (not shown) and the water thereafter flows downwardly over depending sheets on the distributor so that the incoming sea Water has a large surface exposure for evaporation.

The interior of the evaporating chamber 20 is maintained at a low pressure, approximately 3.2 mm. Hg (millimeters of mercury), by a vacuum pump not shown. Due to the fact that the interior of the evaporating chamber is at such low pressure sea water will flash-evaporate therein. At the freezing temperature of sea water, the heat of vaporization is approximately 1074 B.t.u. per pound and the heat of fusion of ice is about 144 B.t.u. per pound. As vapor is produced by evaporation, heat 'is removed from the remaining liquid and ice is formed therein. Due to the diiferences in heat of vaporization and heat of fusion, approximately 7 /2 pounds of water vapor will be produced for each pound of ice produced. The ice so produced is substantially pure water/ ice with no appreciable amount of salt contained therein. When continuous operation is established, the temperature Within the evaporating chamber will be approximately 248 F. The vapor formed will be pure water vapor. Thus, upon removal of the pure water from the incoming sea water by the vaporizing and freezing, the remaining sea water becomes .a more concentrated salt solution.

While theoretically in excess of pure water by Patented June 14, 19 66 3 weight could be removed in the form of vapor and ice, we have found that removing approximately 50% by weight of pure water is in the range of greatest efficiency; thus, if approximately 50% of the water is removed as vapor and ice, the remaining brine solution will consist of approximately 7% by weight of salt.

The evaporation of Water, with the consequent formation of vapor and ice, is a function of time since heat must be transferred, and also the rate of evaporation is proportional to surface area. In order to have the sea Water remain in the evaporating chamber for a sufficient period of time and to offer large surface exposure of the sea water, a distributor means (not shown) is disposed within evaporating chamber 20.

The brine, with the ice crystals therein, is withdrawn from the bottom of evaporating chamber 20 through pump 24, and this mixture has a temperature of approximately 24.8 F. The mixture is delivered to separator washer or counter washer 26, in which the ice is separated from the concentrated brine and the ice is washed free of salt adhering to the surface of the ice crystals. The ice-brine mixture enters the lower end of the separator-washer under pressure and the column of the separator-washer becomes essentially full of ice crystals. The pressure exerted by the entrance of the brine at the bottom of the counter washer forces the cylinder of ice packed therein upwardly, and this brine forces its way through the ice pack, out through screens 28. A pump 30 removes the brine from jacket 32 around the lower end of the counter washer. The pressure drop, created by forcing brine through the ice pack within the column, exerts a force on the column of packed ice moving it up wardly. Thus, the ice column Within the counter washer continuously moves upwardly. At the upper end thereof is a motor-driven scraper or wiper 34 which wipes off the top of the upwardly moving column of ice and delivers the ice into trough 36. Spray heads 38 are provided at the top of counter washer 26 for spraying sweet water supplied by pipe 40 onto the top of the porous column of ice, which water runs downwardly over the advancing column of ice to wash away any adhering brine on the surface or in the interstices of the ice.

Sweet water is added by means of pipe 42 to the ice in trough 36 so as to produce a solution of sweet water and ice suspended therein which can be pumped.

By supplying sweet water to the ice to provide a liquid with the ice suspended therein, the resulting material may be more readily handled, and the liquor prevents the breaking of the vacuum within the vacuum chamber. Ice-sweet water pump 44 is shown for delivering the material through pipe 46 to a plurality of trays (not shown) arranged concentrically within a condensing chamber 50.

Condensing chamber 50 is an annular chamber, having its inner dimension defined by the wall of the concentric evaporating chamber 20 and its outer dimension defined by the outer wall 52, which preferably is insulated as indicated in FIG. 1 to prevent heat from entering the system.

The radial compressor generally indicated at 54, which forms the subject of this application, is positioned within the upper end of condensing chamber 50 and has an axial intake opening 56 in communication with evaporating chamber 20 and a circular outlet 58 communicating with condensing chamber 50.

Vapor formed in evaporating chamber 20 is drawn into central inlet 56 of compressor 54 and delivered radially outward into condensing chamber 50 through outlet 58. The vapor is thus compressed and compressor 54 maintains condensing chamber 50 at a pressure of approximately 4.6 mm. Hg. The vapor delivered by the compressor into the condensing chamber passes downwardly into contact with the ice disposed in trays (not shown) and simultaneously causes the vapor to condense and ice to melt. The sweet water thus produced is withdrawn from the lower end of condensing chamber 50 through pipe 60, which delivers a portion of the sweet water back to counter-washer 26 through pipes 40 and 42 for ice washing and for mixing with the ice. The majority of the sweet water product passes through pipe 62 to heat exchanger 16.

One of the greatest difiiculties encountered in prior art vacuum freezing systems in their inability to eificiently and economically handle and transport the large volumes of vapor that exist for any system producing a meaningful amount of sweet water, particularly when it is recognized that we are dealing with such low pressures that approximately 4,500 cubic feet of vapor at these pressures is required to provide one pound of water vapor. Without the arrangement and apparatus of this invention, expensive and extremely large compressors, shrouds and conduits would be required for handling the vapor. Normally, to move any such large volume, a multi-stage axial compressor would be required and the cost of the impellers and housings without considering the conduit size and expense would make the system uneconomical.

Additionally, by positioning the compressor within one of the chambers, the pressure differential across the shroud is so slight that a very inexpensive shrouding may be used on the compressor. In essence, the housing of the vessel into which the compressor discharges is the real structural support housing of the compressor.

Likewise, with the arrangement proposed, the compressor serves as a self-regulator upon the system since the amount of vapor that can be handled by the compressor will control the rate at which vapor is formed by vaporization and the rate at which it is condensed.

Ideally, the vapor should be delivered to the evaporating chamber at saturation conditions of pressure and temperature so that the vapor will condense on the 32 F. ice and the ice will take out of the vapor 1,074 B.t.u. per pound of vapor condensed and thereby cause the 32 F. ice to melt by each pound absorbing 144 B.t.u. However, due to losses because of heat entering the system and superheating of the vapor, secondary refrigeration coils 64 are provided in condensing chamber 50. These coils condense enough vapor to provide thermal balance in the process. The coils 64 are cooled by a conventional refrigeration unit 66 in which sea water, tapped from sea water inlet 10, may be circulated and then discharged through waste outlet 68.

The motor 70 for driving the compressor is located outside of condensing chamber 50 sothat it will not introduce heat into the system, and the drive mechanism between the motor and the compressor is of a unique type. Motor 70 is flooded with water delivered to the motor housing by pump 72'through pipe 74 and this water is circulated through the motor housing and discharged through pipe 76. This drive mechanism provides an effective seal for the drive shaft of the compressor, without the use of expensive and elaborate mechanical seals, which are normally required for such high pressure differentials by allowing leakage of sweet water from the motor housing into the condensing chamber. Sweet water flowing in the motor housing cools the motor and that portion of the sweet water leaking into the condensing chamber flashevaporates to cool the compressed vapor and partially reduce the super-heat in the vapor.

As previously described, the final product, potable water, is delivered from condensing chamber 50 through pipe 62 to the heat exchanger 16 and is at a temperature of approximately 32 F. The concentrated brine which has been separated from the ice in counter-washer 26 is delivered via pump 30 to the heat exchanger through pipe 78 and is at a temperature of approximately 24.8 F.

The purpose of the heat exchanger is to cool the incoming sea water to the maximum extent possible by withdrawing heat therefrom and delivering it to the cold brine and sweet water produced, and it is important that the sea water be cooled as efiiciently as possible. With heat exchanger 16, approach temperatures of about 2 F. have been achieved and, thus, sea water entering the system through cold sea water pipe 18 is at about 302 F.

The sweet water, as it leaves heat exchanger 16 through pipe 80, is the principal product of this system and is delivered to storage tank 82 from which it may be withdrawn for use. The warmed concentrated brine, as it leaves heat exchanger 16 through pipe 84, is delivered to the waste outlet 68 for return to the sea or for other use or disposal.

It should be noted that a higher pressure is necessary in the condensing chamber than in the evaporating chamber because the vapor pressure of the freezing brine is lower than the vapor pressure of the ice-water mixture at 32 F.- The vapor pressure of brine of 7% by weight salinity at 24.8 F. is about 3.2 mm. Hg, while the vapor pressure of ice-water mixture at 32 F. is about 4.6 mm. Hg. The compressor maintains this condition.

It has been found advisable to recirculate a portion of the cold brine in order to prevent ice from building up within the evaporating chamber and thereby plugging the system and stopping continuous operation. Thus, a portion of the cold brine taken from counter-washer 26 is delivered by pump 30 into pipe 86, which connects with the distributor means (not shown) in chamber 20, which has a spray head.(not shown) disposed at the bottom thereof in the evaporating chamber. Likewise, a portion of the cold concentrated brine is delivered by pump 30 through brine pipe 78 and intermediate pipe 92 to incoming cold sea water pipe 13. Thus, cold concentrated brine is mixed into incoming sea water and passes through the evaporating chamber 20 over the distributor means (not shown) therein, and this mixture is joined at the bottom of evaporating chamber 20 by sprayed-in concentrated brine from the spray head in the evaporating chamber 20. A suitable distribution means is shown in the copending US. application of John Hans Davids, Serial Number 85,522, filed January 30, 1961, now Patent No. 3,103,792, the disclosure of which is hereby incorporated by reference herein. This introduction of concentrated brine with the sea waterdoes not interfere adversely with the evaporation and formation of vapor and ice, but conversely does prevent ice from building up on a distributor. In addition, small ice crystals escaping from the drainage area of the counter-washer are thus reintroduced into the system to promote crystallization. Also, the greatest amount of ice is present in the ice-brine mixture at the bottom of evaporating chamber 20 and there is a tendency for ice build-up at that point. However, the introduction of additional brine increases the fluidity of the total mixture and also has a flushing action at the bottom of the evaporating chamber.

In any commercially successful desalination system,

relatively large volumes of potable water must be produced and, while this may be effected by building larger and larger equipment, and, within shadow of commercial unacceptance due to high cost, the size of the equipment must be reasonable. With the system, schematically shown in FIG. 1, it is contemplated that approximately 60,000 gallons of potable water per 24-hour day would be produced. Rather than attempt to increase the size of the equipment and thereby add to its expense out of proportion to gain, it is contemplated that when larger production of potable water is required, which will normally be the case, separate but parallel systems will be installed and ope-rated to supply additional requirements.

By referring to FIG. 2, it Will be seen that compressor 54 is disposed within the outer housing of the condensingevaporating chambers. In the particular embodiment, the compressor is disposed immediately below cover 110 of chamber and above cylindrical Walls 94 of evaporating chamber 20. The compressor is actually supported by this cove-r and comprises a housing or shroud 134, having a top housing 136 and a lower housing or shroud 138, which are preferably constructed of fiber glass and which are secured together but spaced apart around the periphery of the compressor by attachment means 140. Bottom shroud 138 is provided with the previously mentioned central inlet 56, and the annular space between the top and bottom shrouds, ext-ending completely around the compressor, provides the circular outlet 58 previously identified. Shroud-s 136 and 138 are so sealed to the walls of the chambers that the only communication between the chambers is through central inlet 56, the interior of the compressor, and circular outlet 58.

Mounted within housing 134 on a common shaft is a rotating impeller 142 and a flow inducer 143 (FIG. 2) and it is important to note that this impeller is bearinged within and supported by the top cover of condensing chamber 50. The housing 134 does not journal or support the impeller 142 and the housing is a lightweight shroud fully supported by cover 110, which with the other walls is the effective support and heavy-duty housing for the compressor. As seen in the drawings, the shroud or housing 134 is of thin, light construction." Impeller 142 comprises a plurality of pairs of radially extending blades 144, each pair having a common b-ight, and central hub 146 and is rotated by motor 70 within housing 134. It must be appreciated that in order to move the volume of vapor required, this compressor is large and rotates at a relatively high speed. For example, the diameter of impeller 142 will be approximately 7 feet and the speed of rotation will be 3,600 rpm. For. such speed of rotation and size of impeller, it is, therefore, most important that a strong and yet lightweight rotor be provided. Since cover 110 is a substantial structural member, it is able to afford the necessary shroud or covering for the impeller and is of relatively light material. In essence, the chamber into which the compressor is discharging serves here as the housing for the compressor and support for the drive.

While the system is operating and the compressor is rotating, vapor formed-within evaporating chamber 20 is drawn into central inlet 56, and is moved by rotating bladed inducer 143 and rotating blades 144 radially outward at progressively increasing pressure for ultimate discharge through circular outlet 58 into condensing chamber 50. In other words, the compressor affords a direct radial path for movement of the vapor. Important also is the fact that vapor will be drawn into the compressor throughout the entire area of central inlet.

opening 56 and discharged throughout the entire area of circular outlet 58. Thus, vapor will be delivered around the entire annular area, of condensing chamber 50 for movement into contact with the ice that has been spread out within substantially the entire area of the condensing chamber. With this concentric chamber and compressor arrangement, vapor will move from all points of discharge from the compressor in a spiral path downwardly through the condensing chamber maintaining the high velocity imparted to the vapor by the compressor. Since condensation is a function of surface contact and velocity of relative flow, this is, of course, advantageous. The advantages of the arrangement with regard to size and cost of equipment must be emphasized and appreciated and this close-coupled relationship of the'compressor and chambers accomplishes these advantages. It a conventional volute type casing for a compressor were utilized, its diameter would be about 14 feet and to convey the volume of vapor contemplated for the type of equipment shown, ducts having diameters of approximately 6 feet would be required. Equipment of this size obviously introduces thermal losses into the system and the cost of the parts and of insulation becomes substantial.

To a large degree vacuum freezing desalination systems have heretofore been penalized because of the failure to provide efiicient and economical equipment for and are rangements of the compressor and condensing and evaporating vessels. With the arrangements contemplated in the past to move such a large volume of vapor, one would normally use an axial compressor having several stages.

The cost of such a compressor arrangement alone, and certainly when combined with the cost of providing evaporating and melting vessels, would most likely exceed the permissible cost for an entire system for desalination.

COMPRESSOR CONSTRUCTION Referring first to FIG. 2, as before indicated, the presently improved compressor generally indicated at 54 is particularly suitable for use in the aforementioned potable water-producing system. Compressor 54 is mounted in the upper zone of the chamber 50 and overlies the upper end of evaporating chamber 20 with its intake port 56 open to the chamber 20. The compressor I discharge outlet 58, peripherally thereof, is directly open to the condensing chamber 50.

As shown by FIG. 2, the compressor 54 is an axial intake, radial discharge unit of improved and compact construction. It includes a two-part housing or casing 134 of metallic or non-metallic material, as suitable sheet metal of corrosion-resistant character or suitable plastic, fiber glass, or other similar material, comprising an upper wall-forming member or housing 136 of circular periphery, and a lower member or shroud 138, also of circular periphery and spaced from the upper member to form.

the rotor chamber 164 therebetween. Assembly connection of the members 136 and 138 is made by a plurality of attachment means and spacer elements 140 relatively spaced about the peripheral region of the housing in connection to the respective peripheral end portions 166 and 168 of the members. Such end portions define therebetween the compressor discharge outlet 58 which is open circumferentially of the housing. Member 138 is formed to provide a wall 170 of predetermined shallow frusto conical form between the generally radial end portion 168 and an out-turned circular flange 172, the latter defining the axial inlet eye or intake port 56 of the compressor. The upper member 136 is formed to provide a similar but oppositely directed shallow frusto-conical wall section 174 inwardly from its generally radial end portion 166, merging into the inner wall section 176 which lies in a radial plane normal to the rotor axis of the compressor. Thus, in sectional view (FIG. 2), the two wall sections 170 and 174 converge toward the discharge outlet 58 from a zone which, in the present example, is slightly radially beyond the inlet flange 172. While the described frusto-conical wall section 174 is preferred in member 136, this member could be provided as a uni formly flat or planar member with corresponding increase in the angle of taper of the lower wall 138.

The compressor housing is mounted within the upper end of the device in a horizontal position over the cylindrical wall side 94 of evaporating chamber 20, wall 94 providing a circular central aperture 178 to receive the compressor inlet flange 172 therethrough. Support of the housing is effected from the top wall or cover 110 as by bolting at 180 to a plurality of tank strengthening ribs 182 depending from top wall 110. As shown in FIG. 2, the lower housing member 138 includes an external, depending annular flange 184 which seats in compressive engagement with resilient seal element 186, of rubber or the like, carried in an annular chamber 187 on the outer overhanging margin 190 of the end Wall 192 of chamber 20. Each rib 182 terminates in a lateral projection forming a pad against which the flange 166 of the compressor housing wall 134 abuts, such pad serving to effect the desired assembly location of the wall. Due to the vacuum in the chambers, considerable load will be exerted on cover 110 to cause deflection thereof, but since compressor 54 is supported and carried thereby, no problems to the compressor result from this deflection.

Referring to FIGS. 2 and 4, operative in the housing as above described is a compressor rotor assembly or rotatable impeller 142 comprising a hub structure 146 on a vertical drive shaft 196, and a plurality of generally radial blades 144, constructed in accordance with the present invention, projecting from the hub. The hub structure comprises a shaft-mounting sleeve hub 19 8 keyed to, pressed on, or otherwise fixed to drive shaft 196 and held thereon as by a retainer plate 200 bolted to the shaft, and a blade hub 202, here shown constructed in one piece, secured as by bolts 204 to the flange portion 206 of the shaft hub 198.

Referring to FIGS. 2 and 4, formed in the hub 202 are a plurality of circular through bores 208 parallel to the shaft axis, these being inwardly adjacent to the hub periphery and equi-angularly spaced circumferentially of the hub. Each bore 208 has a radial slot 210 of predetermined width, opening the bore to the hub periphery, the slots as well as the bores being open at each side face 212 of the hub. The bores and slots form blade mounting seats.

Each blade 144 is formed from a strip of flexible sheet material having a predetermined thickness. The blade material' here used is fiber glass, or corrosion-resistant metal, as stainless steel or the like. In blade formation, an elongate rectangular strip of predetermined length and width, exemplary dimensions being shown on the drawing, is lengthwise reversely turned or folded upon itself, folding being about a round bar or arbor (not shown) at the strip center, to provide a pair of blades 144 having a common bight or a hollow circular enlarged or eye portion 208 at one common end. Each pair of blades over their outer end section 222 (FIG. 12) is marginally cut or reduced on one side to provide a blade margin 224 such that the blade will have a running clearance in the converging zone of the compressor housing formed by the Wall portions and 174, FIG. 2.

As appears in FIG. 2, there is preferably mounted to the hub 146, as by bolts 298 for rotation therewith an inducer rotor hub 300. The inducer hub 300 is provided with a plurality of circular through bores 302 extending parallel to the shaft axis and being inwardly adjacent to the hub peripherally and equi-angularly spaced circumferentially of the hub. Each bore has a radial slot 304 of predetermined width opening the bore to the hub periphery, the slots as well as the bores being open at each side face 306 of the hub (FIG. 3). The bores and slots form inducer blade mounting seats.

A pair of inducer blades 308 and 310 are fromed from a flexible single stock blank of strip sheet material (FIG. 6), such as metal or a plastic fiber glass material, having a predetermined thickness and contour (FIGS. 3, 6-11, and 13). The strip of sheet material is bent around a round bar or arbor (not shown) at the strip center to form a common bight 311 (FIG. 13) and thereby provides a pair of blades (FIG. 3) having an enlarged common eye portion at one end. An inducer arrangement is provided, of course, to control or direct flow of vapor from the chamber 20 to the impeller of the compressor.

The inducer blades are preferably provided with a bucket shape for eflicient operation thereof. To this end, the outer ends 318 of each blade 308 and 310 are preformed before bending of the stock strip (FIG. 6) to provide the bucket shape thereto. The strip 312 is bent at a plurality of locations at predetermined angles at each end thereof substantially along the dotted lines shown in FIG. 6 to provide flanges defining the desired bucket shape. For example, referring to FIGS. 6 and 8, a strip 312, having the exemplary dimensions shown in FIGS. 5-7, may be bent along line 88 of FIG. 6 and at the angle indicated in FIG. 8 to provide the flange 31.6 with the dimensions indicated in FIG. 8. Similarly, the strip may be bent at other locations as indicated in FIGS. 9, 10 and 11 at locations shown in FIG. 6 and at the angles indicated in these figures to provide the flanges 316 with the dimensions noted in these figures. It will be appreciated, of course, that the dimensions given are exemplary only and that, depending upon the requirements of the rotor arrangement desired, these parameters of the inducer blade may be determined by employment of known computation methods.

After the flanges 316 have been formed on the strip 312 at each end thereof, the strip 312 may be bent at its center around an arbor (not shown) to form the two blades 308 and 310 having the common bight 311 (FIG. 13).

Secured to the inducer rotor by bolts 298 (FIG. 2) is a mounting plate 318 for a rod 320 which carries a semi-hemispherical shell 322 of rigid material, such as fiber glass or stainless steel. The shell is centrally carried near the top of the chamber 20 and serves as a streamline surface which cooperates with the inducer arrangement of the present invention to direct the flow of vapor from chamber 20 to the impeller-of the compressor.

BLADE MOUNTING ARRANGEMENT The compressor blade mounting arrangement is similar in construction to the inducer'blade mounting arrangement, and, thus, the description to follow of the inducer blade mounting arrangement, it will be appreciated, applies equally to the description of the impeller blade mounting arrangement.

After each of the strips 312 has been bent upon itself to form a pair of blades 308 and 310 having a common bight 311, the bight of each pair of blades is longitudinally inserted in a bore 302 of the blade hub 300 in such a manner that the blades 308 and 310 extend through the corresponding slot 304 in the hub 300 (FIG. 13). It will be observed that the bight 311 of the blades 308 and 310 is of lesser dimension than the bore 302. Such sizing of the bight 311 facilitates contouring of the bight to the bore 302 and permits expansion of the bight to the dimension of the bore.

To contour and expand the bight, a tapered tap tool 322 (FIG. 14) is forced from the top or bottom of the rotor 300 into the space-defined by the bight 311 to spread and contour the bight. The tap tool 322 is provided with a tapered elongated conical portion 323 which is inserted first into the space defined by the bight 311 and is also provided with a head 324 of cylindrical external configuration which is of a diameter corresponding generally to the diameter of a removable pin 326 (FIG. 15) which is employed to secure the common bight in the bore and to prevent lateral translation of the blades 308 and 310.

After the head 324 of the tool 322 has been forced into the space defined by the bight to spread the bight and to force it in contact with the wall of the hub 300 defining the bore 302, the hollow pin 326 (FIG. 15) is placed on top of the head 324 and forced into the space occupied by the head 324 which results in removal of the tool 322 from the said space. The hollow pin 326 is forced into the space defined by the inner surface of the bight 302 until the top surface 327 and bottom surface 328 of the pin are flush with the corresponding surfaces 301 of the hub 300 as appears in FIG. 16.

With the pin 326 in the position shown in FIG. 16, the blades 308 and 310 assume the position shown in dotted lines in FIG. 17.

Experience has indicated that pairs of blades constructed in accordance with this invention and employed for moving large quantities of vapor under vacuum conditions has a short use life because the blades had a tendency to break at the points a (FIGS. 3, 13 and 17) Where the radius R of the blade bight curves to join the blades 308 and 310. This experience was obtained as the result of employing only the pin 326 to seat the pair of blades, and if one of the blades broke, the other blade would, due to the forces acting thereon, pull out of its seat.

A feature of the present invention resides in the provision of means for initially contouring the blades at points a to correspond to arcuate surfaces 330 of the webs 332 defined by adjacent bores 302 and by the provision of strengthening means herein-after described which are employed to maintain the blades contoured at points a during operation of the impeller and inducer assemblies.

Means for initially contouring the blades at points a to the arcuate surfaces 330 may take the form of a wedging tool, generally indicated by the numeral 334 in FIG. 17, and which comprises a handle 336 and a head 338. The head 338 is provided with a concave outer surface 340 having a curvature corresponding to the outer curvature of the pin 326 against which the surface 340 is designed to rest. The side walls 342 and 344 of the head 338 are convergingly tapered and of a width dimension corresponding to the width dimension of the blades 308 and 310. In use, the tool head is inserted between the blades 308 and 310 when in the positions shown in dotted lines in FIG. 17 and the tool pushed inward to spread the blades 308 and 310 until the head surface 340 engages the outer surface of the .pin 326, as shown in full lines in FIG. 17. When the surface 340 engages the pin 326, the side walls 342 and 344 of the head 338 spread the blades 308 and 310 and is so doing bend and contour the blade at points a to the configuration of the arcuate surfaces 330 of the webs 332.

The tool head 338 is removed from contact with the pin 326 and after removal of the tool, the blades will have a pre-formed contour at points a.

The-means for maintaining the blades in position with the common bight seated in the bore of the rotor head may, in accordance with the present invention, take the form of a U-shaped wedge shoe 346 (FIG. 3) of a length corresponding to the thickness of the hub 300. The shoe 346 is provided with an arcuate body portion 348 and depending parallel flanges 350 and 352. The flanges each have an edge in line contact with pin 326 when the shoe is removably secured to the pin 326 by a screw 354 threaded through an aperture in the shoe 346 and through a corresponding aperture 356 in the pin 326. The shoe 346 spreads the blades 308 and 310 when in threaded engagement with the pin 326 in such a manner that the side walls 358 and 360 of the flanges 352 and 350 urge the blades 308 and 310 against the webs 332 and cooperate with the pin 326 and webs 332 at points a to maintain the blades at these points in contact with the arcuate surfaces 330 of the webs 332.

With the shoe arrangement shown in FIG. 3, the blades do not have a tendency to break at points a during the normal expected use life of the compressor assembly.

To further strengthen the blades at the roots thereof and to minimize the effects of vibration on the blades at the roots thereof during operation, a plurality of U-shaped damping clamp wedge members 364 are employed around the periphery of the hub 300, where, for example, sixteen bores are formed in the hub thus providing for employment of sixteen pairs of blades 308 and 310.

The wedge members 364 are U-shaped or wing-shaped in configuration and comprise a body portion 366 in engagement with the body 348 of the shoe 346. The body has extending therefrom flexible flanges 367 and 368. The flanges 367 and 368 each engage the inner surface of the blades 308 and 310, respectively. The wedge member 364 is preferably secured in engagement with the shoe 346 by means of the screw 354 passing through a threaded aperture in the body portion 366 thereof. When in the position shown in FIG. 3; the flanges 367 and 368 maintain the blades 308 and 310 in spaced-apart relation. A plate 370 may be employed to distribute the pressure applied to the wedge during threading of the screw 354. The wedge members 364 may be constructed of sheet material stormed with the flanges 367 and, 368 and bored and threaded for receiving the screw 354.

It will be observed that the wedge members 364 are designed to dampen out the effects of vibrations on the blades 308 and 310. A plurality of second damping clamp wedge members 372, corresponding to the configuration of the wedge members 364, are provided with a body portion 374 and flexible flanges 376 and 37-8. The body portion 374 is apertured and threaded to receive a threaded screw 380 which secures the wedge member 372 to the web 332 which is bored and threaded to receive the screw 380; It will be observed that the flanges 376 of the wedge members 372 cooperate with the adjacent flanges 368 of the wedges 364 to support the blades 310 adjacent the common bight 311. Similarly, the flanges 378 of the wedge members :372 cooperate with the adjacent flanges 367 of the wedges 364 to strengthen and suppont the blades 308 adjacent the common bight 311. It will be appreciated that the plurality of alternative first wedge members 354 and second wedge members 372 positioned around the periphery of the hub 300 cooperate to provide a blade support and strengthening arrangement for a plurality of pairs of blades 308 and 3&0, each pair having a common bight 311. A plurality of plates $82 and 384 may be provided for distributing the force applied to body 374 of the wedge members 372 by the screws 380.

To complete the mounting of the pairs of blades 308 and 310 in the bores 302, pipe plugs (not shown) may be threaded into the ends of the pins 326 (FIG. 16) and the pins may be provided with slots 390 for expansion thereof by the pipe plugs to lock the blades in position.

Referring to FIGURE 4, it will be observed that the same blade mounting arrangement and strengthening means are employed for the compressor hub 202 and rotor blades 144. The blades 144, as aforesaid, are formed in pairs having a common bight, are flat, and do not have i flanges 316.

In assembling the blades of the compressor to the hub 202, as appears in FIG. 4, each pair of blades has a common enlarged end or eye 218 inserted and seated in one of the hub bores 208 with the blades projecting outwardly therefrom through the associated bore slot 210. The outer diameter of the common bight or blade eye 218 is such as to effect a snug fit thereof in the bore, while the Width of the bore slot 210 is such as to closely confine the blade portions extending therethrough. The webs 395 (FIG. 4) of the hub are provided with an arcuate surface 397 at points a and the blades are bent at these points as indicated above in connection with the description of the mounting of the inducer blades 308 and 310. Pipe plugs (not shown) may be employed to close the ends of the pins 326 having the slots 390 therein.

The blades 144 thus mounted on hub 202 extend therefrom in the compressor housing rotor chamber 164 with the reduced or convergingly tapered end portions 224 thereof in close running fit in the converging zone of the housing provided by walls 170 and 174. These rotor blades 144, being constructed of thin sheet strips in the manner described, afford lightweight flexible blades which, mounted as shown and described, permit high-speed operation of the rotor. The blades have a predetermined minimum thickness as, for example, approximately two hundredths of an inch (.02 inch) in a blade having a length of about thirty one (31) inches and a width of about nine (9) inches inwardly of its tapered end. This minimum thickness is sufficient for structural self-support of the blades in displacing water vapor under the heretofore indicated sub-atmospheric pressures, as the blades being flexible, will assume positions of radial extension from the hub under the influence of centrifugal forces thereon in compressor operation. Thus, the improved rotor structure is one which will be economically constructed with easy-to-fabricate blades and a simple yet highly eflicient blade-mounting and damping arrangement. The thin blades formed in the manner described, facilitate desired high-speed rotation of the rotor under vacuum conditions and such high-speed operation is further facilitated by the absence of rotating blade shrouds.

The compressor as herein illustrated and now described is designed and fully effective for handling water vapor in large amounts and at a relatively low compression ratio, under the desired sub-atmospheric conditions. In this construction, the opening sides or diameter of the compressor inlet eye 56 is determined in accordance with the desired velocity of vapor intake and flow rate in the compressor. As illustrated in the present example, the inlet is of relatively large diameter and open to the blades over approximately the inner half lengths thereof. Also, since the degree of vapor compression is dependent on rotor speed and the outer diameter of the rotor blading, these factors are selected to obtain the desired com: pression ratio suitable to the purpose of the system referred to. A compressor constructed in accordance with the present invention under operating conditions is required to move approximately two hundred thousand ft, vapor per minute to obtain sixty thousand gallons per day of the final product, sweet water.

It will be observed that the weight of the compressor assembly is relatively light when compared to comparable compressor assemblies. Moreover,the rotor, itself, serves as a tool in the formation and mounting of the pairs of blades, which formation would be otherwise difiicult to achieve because of the high-spring back characteristics of the material employed for blade construction. Preferably, the rotor hubs and the pins 326 are plated with a corrosive resistant material, such as tin. It will also be appreciated that with the present invention the area of greatest cost of manufacture, i.e., blade construction and mounting to the hub, has been minimized.

It is to be noted that the straight peripheral portions or margins 166 and 168 of the compressor housing, defining the compressor outlet 58 which is open circumferentially of the compressor, forms a diffuser wherein the dynamic energy of the discharged vapor is converted to static pressure. Such diffuser may be extended to form a continuation of the compressor housing wall member 138 and, cooperating with the adjacent top portion 110, provides a downwardly directed annular outlet into condensing chamber 50.

From the foregoing, it will be seen that the compressor and compressor rotor are of extremely simple, compact and eflicient construction and yet economical in cost and high speed in operation.

The rotor assembly has blades of thin sheet material in a flexible mounting on a central hub and can handle large volumes of vapor at a relatively low compression ratio under the given sub-atmospheric pressure conditions with the blades assuming operative positions responsive to centrifugal force.

Although the present application describes the presently preferred embodiment of this invention and is shown in connection with the system of producing potable water from sea water, it will be appreciated, of course, that the present invention has utility in other application.

Although various minor modifications of the present invention will become readily apparent to those versed in the art, it should be understood that what is intended to be covered by the patent granted hereon are all such embodiments as reasonably and properly come Within the scope of the contribution to the art hereby made.

We claim:

1. In the method of producing a bladed rotor, the steps comprising: bending a flexible strip of sheet material lengthwise upon itself at approximately its center to form two integral elongated rotor blades of the same length having a common bight portion at the bend of the strip, forming a generally axial bore in the rotor hub opening out of at least one end surface of the hub and providing a generally radial opening in the hub extending from the bore to the periphery of the hub, inserting the common bight portions of the pair of blades in the axial bore with the blades projecting generally radially from the bore and through the radial bore opening, and securing the pair of blades thus formed within said bore.

2. The method of claim 1 including the additional steps of spreading the common bight portion to contour the common bight portion and blades to the interior of the bore defining wall of the hub, and securing the com- 111011 bight portion in the bore with the blades maintained in spread apart relation.

3. The method of claim 1 including the step of securing the blades in a spread apart relation after the bight portion is secured in said hub.

4. The method of claim 1 wherein the bore formed in the rotor hub is semi-cylindrical in configuration and including the additional steps of contouring convexly, relative to each other, each of the areas of the hub Where the bore and said radial opening meet, and spreading the blades at said hub areas to contact the blade portions adjacent said areas with'said areas to thereby contour said adjacent blade portions to the respective curvatures of said hub areas.

5. The method of fabricating rotor assemblies comprising the steps of forming a hub with at least one bore opened to the periphery of said hub by a radial slot, bending at least one elongated strip of sheet material to form a pair of blades having a common eye or bight portion, inserting the bight portion of said pair of blades in said bore with the pair of blades extending through said slot, contouring the bight portion of said pair of blades to said bore, spreading and securing the blades in spread apart relation adjacent the slot and securing the blades to said hub.

6. The method of claim 5 wherein said blades are spread apart and maintained in said spread apart relation 14 by inserting at least one strengthening and vibration damping means between said blades adjacent the slot, and including the step of securing said strengthening means to saidhub. v

7. The method of claim 5 including the step of securing vibration damping means adjacent at least one of said blades.

8. The method of claim 5 wherein said strip of said material is bent to form an eye portion of lesser diameter than said bore, and including the step of expanding the diameter of said eye portion when seated in said bore.

References Cited by the Examiner UNITED STATES PATENTS 1,035,364 8/1912 Leblanc 1031l5 X 2,656,146 10/1953 Sollinger 29-1568 X FOREIGN PATENTS 7,997 2/ 1898 Austria. 561,554 10/1957 Belgium. 332,859 7/1930 Great Britain.

CHARLIE T. MOON, Primary Examiner.

J. C. I-IOLMAN, Assistant Examiner. 

1. IN THE METHOD OF PRODUCING A BLADED ROTOR, THE STEPS COMPRISING: BENDING A FLEXIBLE STRIP OF SHEET MATERIAL LENGTHWISE UPON ITSELF AT APPROXIMATELY ITS CENTER TO FORM TWO INTEGRAL ELONGATED ROTOR BLADES OF THE SAME LENGTH HAVING A COMMON BIGHT PORTION AT THE BEND OF THE STRIP, FORMING A GENERALLY AXIAL BORE IN THE ROTOR HUB OPENING OUT OF AT LEAST ONE END SURFACE OF THE HUB AND PROVIDING A GENERALLY RADIAL OPENING IN THE HUB EXTENDING FROM THE BORE TO THE PERIPHERY OF THE HUB, INSERTING THE COMMON BIGHT PORTIONS OF THE PAIR OF BLADES IN THE AXIAL BORE WITH 